The present invention relates to a device for supplying voltage in a motor vehicle with parallel connected generators.
A device for supplying voltage of this type is known and includes the generators and connected voltage regulators, at least one battery one of whose terminals is connectable via a starter switch with the voltage regulator, and a charge control device which is connectable with both the starter switch and the voltage regulators and also via switching means with the negative terminal of the battery, also advantageously connected to ground.
The production of electrical energy for vehicle power supply occurs advantageously with a vehicle alternator, whose output voltage is adjusted and set with a connected voltage regulator to a value required in the power supply network. Since the demands on the power supply system in a modern motor vehicle are very high, generator systems were proposed which have two parallel connected generators.
For example, it is known from Published European Patent Application 232 828 A2 to use two alternators each with its own voltage regulator for charging two batteries connected in series. Thus both voltage regulators are connected with each other by the charge control lamp and the charge control lamp can be connected with the batteries by the starter switch.
In known generator systems voltage is applied to the charge control lamp after operation of the starter switch so that it is illuminated. Furthermore if the starter is operated, after conclusion of the starting process a voltage is induced in a known way, with whose help the batteries are charged and which puts out the charge control light.
This known arrangement has the disadvantage that defects occurring during operation are not indicated and resulting short circuits can cause damage to one of the generators and also can impair the operation of the other generator.
A voltage regulator or device for supplying voltage is also known and used currently in various motor vehicles, in which the charge control lamp is used to indicate the starting process and defects in the system as they occur. One such arrangement is shown in FIG. 1. Each voltage regulator has an integrated circuit or integrated circuit means connected to the bases of two transistors whose collectors are directly connected with each other and the transistors are connected in parallel with the battery supplying current when the starter switch is closed. In this device, when the starter switch is closed, the charge control lamp lights, and the consuming devices are disconnected from the battery by a relay switch. In normal operation the charge control lamp is shut off and the consuming devices connected. If a defect occurs during normal operation however, the charge control lamp lights signalling the defect to the operator.